Typically the knife on cutting headers comprises a knife bar extending along the front lower edge of the header, with a plurality of triangular knife sections attached to the bar such that the apex of the triangle extends forward from the bar. The exposed side edges of the knife sections are sharpened. Guards are attached to the front lower edge of the header and serve to protect the knife sections from breakage when contacting stones and like obstructions. The guards comprise pointed guard fingers extending forward, and the knife moves back and forth along the edge of the header in a slot cut laterally through the guard fingers. In addition to protecting the knife, the guard fingers also enable the knife sections to cut the crop. As the knife section moves back and forth it pushes crop against the sides of those portions of the guard finger that are above and below the slot, shearing the crop stalks.
Crop accessories such as crop lifters are also conveniently attached to the guard fingers and the guard bolts that attach the guard to the header. Examples of such lifters are illustrated in U.S. Pat. No. 4,120,138 to Schumacher, and in Canadian Patent Number 2,524,343 to the present inventor Dietrich.
In order to mount these crop lifters the guard finger and mounting bolt must be aligned. On the majority of headers the guard bolts and fingers are aligned and the standard crop lifters, which are readily available, can be used. On some harvest headers however, the guard bolts are offset to one side or the other from the guard finger, and so the standard crop lifter cannot be attached, and more costly and less convenient options must be used.